For both seafaring vessels, and fixed position marine based stations, such as offshore installations, the provision of emergency escape vessels, such as lifeboats, is essential. These emergency escape vehicles provide the crew with an escape route in the event of an emergency.
During marine accidents several factors affect the success of evacuation from the installation or ship: the ability of personnel to successfully board the life craft, the ability of personnel to successfully launch the life craft and clear the hazardous area; the ocean and weather conditions during deployment; and the retrieval of the life craft from the ocean. Sometimes, personnel are unable to board the life craft due to the damaged condition of the offshore installation or ship. If personnel do successfully board the life craft they still face the daunting task of launching it. Weather conditions may interfere with, or even prevent launching. If the ocean waves are high, the life craft may be thrown backwards when it touches down on the ocean surface. This action of throwing the lifeboat backward, termed “setback”, may cause the life craft to collide with the offshore installation or ship and injure or kill those on board.
During the deployment of such vehicles, the speed of the descent is controlled to provide an orderly splashdown, simply dropping a loaded life craft from a height is known to be an unacceptable life craft deployment strategy. Typically, life craft are lowered into the water using a hoist, a winch, or other such equipment. Life craft deployment systems are well known in the art, and typically include a controllable motor for raising and lowering the life craft. One of the other benefits of the use of a motorized hoist is that the placement of the life craft is controlled so that a large number of life craft are not deployed in the same area causing congestion and making an orderly escape difficult.
Present evacuation systems lower or drop the life craft into the ocean from the offshore installation or ship at a fixed descent speed. No control is exercised over the drop point target in terms of its position relative to a wave profile. Likewise, the launch of a fast rescue craft is not controlled in terms of its position on a wave profile. Timing a launch is left to the judgement of the coxswain or pilot. One such lifeboat launching system is known as the twin falls davit launch system. This system lowers the lifeboat from a fixed position on the deck of a platform at a fixed rate using cables connected to the bow and the stem of the lifeboat.
During the deployment of a life craft both the wind and the waves on the water surface are a critical factor in ensuring a safe escape. In many instances, the waves and wind are known to push life craft back towards the launching vessel or station, which is highly undesirable. It is known in the art that the initial launch velocity, and the ability of the life craft to provide acceleration away from the launch site is crucial to ensuring a safe launch. The initial headway of the life craft is an important factor in its ability to escape and clear the offshore installation or ship.
Life craft are typically restricted in size for storage reasons, and thus their ability to hold a powerful motor is limited. Thus the ability of the life craft to overcome the effects of wind and waves purely through the power of an onboard motor is limited. As a result there is a need for a life craft launching system that provides an optimal launch location for a life craft so that it can make an improved escape.